ASPxTreeList全面開發(fā)了現(xiàn)存的DevExpress外觀和針對ASP.NET的數(shù)據(jù)管理技術(shù)。個別節(jié)點的按需載入和回叫支持等特點保證方案既優(yōu)質(zhì)又有效。在操作中，更新時控件不必傳輸整個樹結(jié)構(gòu)。ASPxTreeList十分智能，它能夠確定那部分樹結(jié)構(gòu)需要更新，只從服務(wù)器中請求少量記錄，更快地進行用戶交互。

ASPxTreeList-存取和操作數(shù)據(jù)

四種數(shù)據(jù)訪問選項
為了方便您顯示數(shù)據(jù)，ASPxTreeList提供下列數(shù)據(jù)綁定選項：

• 非綁定模式
  您可以采用特別的設(shè)計方法，用代碼構(gòu)建需求的樹形結(jié)構(gòu)

• 動態(tài)節(jié)點載入
  您可以依您的選擇在樹中只填入基層代碼。嘗試用下代節(jié)點擴展上代節(jié)點可以引發(fā)事件，在這里指定需要顯示的下代節(jié)點。這個方法為巨量資料集提供了重要的績效收益。

• 綁定到一個分層次的數(shù)據(jù)源                                                                                                                                 如果您綁定到一個分層次的數(shù)據(jù)源，如Site Map，控件將自動地建立相應(yīng)的樹。

• 綁定到一個標準的數(shù)源
  當綁定到一個標準數(shù)據(jù)源時，您需要兩個服務(wù)域來建立樹。一個服務(wù)域指定某記錄的特定ID,另一個指定上代記錄的ID。

數(shù)據(jù)排序
為了方便定位控件中的記錄，ASPxTreeList允許你排序無限量行的節(jié)點。

正如您所愿，終端用戶只需點擊數(shù)據(jù)列標題，便可輕松地開始排列操作。

數(shù)據(jù)匯總
如果你的web應(yīng)用程序要求分析數(shù)據(jù)，ASPxTreeList的數(shù)據(jù)匯總功能可以讓你把重點放在總數(shù)，而不是處理單個記錄。您可以總結(jié)所有記錄的數(shù)據(jù)或者只總結(jié)具有共同祖先的記錄數(shù)據(jù)。在這兩種情況中，都有5個內(nèi)建功能為您服務(wù)，您也可以使用專門的設(shè)計項目手動總結(jié)數(shù)據(jù)。合計結(jié)果顯示在控件的頁腳或分組頁腳。請注意，每一行并沒有局限只做一個總結(jié)，您可以按照自身需要做任意多個總結(jié)。

條件格式化
為強調(diào)重要的數(shù)據(jù)，更好的顯示不同的值，你可以使用條件格式化。使用這個特性，全部記錄或單個元素都可以依據(jù)他們所包含的數(shù)據(jù)進行格式化。

最簡單的使用情景是強調(diào)具有特定值或上下限值的記錄或元素。除此之外，您還可以申請“彩色表”。這就意味著元素將會使用相同顏色的不同色調(diào)，用小數(shù)字表示亮色調(diào)，大數(shù)字表示暗色調(diào)。

ASPxTreeList-布局和導(dǎo)航特性
以下為您展示ASPxTreeList的一些導(dǎo)航和布局定制特性。

焦點行和選擇行
您能夠啟用焦點行特性來顯示最后一次點擊的節(jié)點。當TreeView用做導(dǎo)航目的時這個功能非常有用...顯示終端用戶的當前位置。當您在單獨的控件中必須顯示代碼細節(jié)時，此功能可以和數(shù)據(jù)瀏覽樹并用。例如，它可以在顯示論壇消息時使用..強調(diào)目前正在顯示其細節(jié)的代碼。

多節(jié)點選擇也是ASPxTreeList內(nèi)建的特征。您可以啟用行中的選擇復(fù)選框，顯示選擇所有表頭的復(fù)選框。

數(shù)據(jù)分頁
假如你的樹包含許多記錄，你能夠分割數(shù)據(jù)為多頁，這樣可以有效使用頁面空間，提高頁面顯示速度。ASPxTreeList內(nèi)建ASPxPager控件允許你通過AJAX callbacks導(dǎo)航頁面。

自定義窗口（字段選擇器）
假如最終用戶需要臨時隱藏列或使隱藏的列顯示，您能夠啟用Microsoft Outlook風格的字段選擇窗口。最終用戶簡單地拖字段到窗口來隱藏它們，拖回列表頭又可顯示它們。

節(jié)點預(yù)覽
為美觀地顯示memo字段，您可以使用ASPxTreeList的內(nèi)建節(jié)點預(yù)覽特性。例如您想使用控件建立一個網(wǎng)絡(luò)論壇，此特性可以幫助您預(yù)覽一個討論引線的個人信息。

The ASPxTreeList fully exploits existing DevExpress appearance and data management technologies for ASP.NET. Features such as on-demand loading of individual nodes and callback support ensure that the solutions you build are both elegant and effective. In our implementation, the control never needs to transmit the entire tree structure when being updated. The ASPxTreeList is smart enough to determine which portion of the tree to be renewed and only requests a few records from the server, making user interaction lightning fast.

ASPxTreeList - Access and Manipulate Data

Four Data Access Options

To ensure that your data can be easily displayed within the ASPxTreeList, we provide the following data binding options:

• Unbound Mode
  You can build the desired tree structure in code using specially designed methods.
• Dinamic Node Loading
  At your option, you can populate only root-level nodes within the tree. Attempts to expand parent nodes with children will raise an event wherein you can specify the child nodes to be displayed. This approach offers significant performance gains against large datasets.
• Bind to a Hierarchical Data Source
  If you bind to a hierarchical data source, such as a site map, the control will automatically build the corresponding tree.
• Bind to a Standard Data Source
  When binding to a standard data source, you need to have two service fields to build a tree. One should specify a record's unique ID and the other should specify the parent record's ID.

Data Sorting

To make it easier to locate records within the control, the ASPxTreeList allows you to sort nodes against an unlimited number of columns.

As you might expect, end-users can easily initiate sort operations by simply clicking column headers.

Data Summaries

If your web application requires data analysis, the data summary feature of the ASPxTreeList allows you to focus on the overall numbers instead of having to deal with individual records. You can either summarize data across all records or only those records with a common parent. In both instances, five built-in functions are at your service or you can manually summarize values using a specially designed event. The aggregate result is displayed within the control's footer or group footer. And note that you aren't limited to a single summary per column - you can calculate as many summaries as needed.

Conditional Formatting

To highlight important data or better indicate differences between values, you can use Conditional Formatting. With this feature, entire records or individual cells can be formatted depending upon the data they contain.

The simplest use scenario is to highlight records or cells that have a particular value or that have values above or below a particular limit. Beyond these, you can also apply a "color map". This means that cells will use shades of the same color - lighter shades for smaller numbers and darker shades for higher numbers.

ASPxTreeList - Layout and Navigation Features

The following are just a few of the navigation and layout customization features available to you within the ASPxTreeList.

Focused and Selected Rows

You can enable the focused row feature to indicate the last clicked tree node. This is useful when using the Treeview for navigation purposes...indicating the end-user's current position. It can also be used with data-browser trees when you must display node details in a separate control. For instance, it can be used when displaying forum messages...highlighting the node whose details are currently displayed.

Multi-node selection is also a built-in feature of the ASPxTreeList. By toggling a single option, you can enable selection checkboxes within rows and display a Select All check box within the header panel.

Data Paging

If your tree contains many records, you can split data across multiple pages and thus guarantee a more efficient use of page space and faster initial page rendering. If you do so, the ASPxTreeList displays a built-in ASPxPager control allowing you to navigate to the required page via AJAX callbacks.

Customization Window (Field Chooser)

If end-users need to temporarily hide columns or make hidden columns visible, you can enable a Microsoft Outlook style Field Chooser window. End-users can simply drag fields to the window to hide them and then drag them back to the column header panel to make them visible again.

Node Preview Sections

To elegantly display memo fields, you can use the ASPxTreeList's built-in node preview feature. For instance, if you use the control to create a web forum, this feature allows you to preview individual messages within a discussion thread.